Rotary hook

Abstract

A fully rotating hook includes an inner bobbin case, an outer loop taker mounted about the bobbin case, the loop taker having a track groove formed therein, a rotating member for rotating the loop taker such that relative rotation occurs between the loop taker and the bobbin case, and a stopper member for preventing rotation of the bobbin case with the loop taker while the loop taker is rotating. The track groove of the loop taker is formed by at least one wall therein which is coated with a layer of synthetic resin material having a small coefficient of friction to reduce friction between a track projection member on the bobbin case and the track groove of the loop taker.

What is claimed is: 
     
       1. A fully rotating hook comprising an inner bobbin case extending in an axial direction, an outer loop taker mounted about said bobbin case, said loop taker having a track groove formed by at least one wall therein, means for rotating said loop taker such that relative rotation occurs between said loop taker and said bobbin case, and stopper means for preventing rotation of said bobbin case with said loop taker which said loop taker is rotating, said inner bobbin case comprises a case body having a fitting portion extending in said axial direction and accommodated in said loop taker and a track projection member made of synthetic resin material having a substantially low coefficient of friction and removably fixed to said fitting portion of said case body, said track projection member comprising a flange-like track projection fitting within said track groove of said loop taker and a surrounding portion extending in said axial direction for fixing said track projection member to said fitting portion of said case body, said fitting portion of said case body being smaller than the remainder of said case body to form a stepped portion therebetween and said track projection member being fitted to said case body with said track projection fitted against said stepped portion, and said track groove of said loop taker includes a coating layer of porous synthetic resin material having a small coefficient of friction and small holes therein for retaining lubricant oil, wherein said loop taker has three walls defining said track groove and said coating layer is U-shaped so as to correspond to said three walls. 
     
     
       2. The rotating hook of claim 1, wherein said loop taker comprises a steel body. 
     
     
       3. The rotating hook of claim 1, wherein said loop taker includes adhesive means for bonding said coating layer to said track groove. 
     
     
       4. A fully rotating hook comprising an inner bobbin case extending in an axial direction, a metal loop taker mounted about said bobbin case, said loop taker having a track groove formed by a bottom wall and a pair of side walls therein, means for rotating said loop taker such that relative rotation occurs between said loop taker and said bobbin case, and stopper means for preventing rotating of said bobbin case with said loop taker while said loop taker is rotating, the improvement wherein said inner bobbin case comprises a case body having a fitting portion extending in said axial direction and accommodated in said loop taker and a track projection member made of synthetic resin material having a substantially low coefficient of friction and removably fixed to said fitting portion of said case body, said track projection member comprising a flange-like track projection fitting within said track groove of said loop taker and a surrounding portion extending in said axial direction for fixing said track projection member to said fitting portion of said case body, said fitting portion of said case body being smaller than the remainder of said case body to form a stepped portion therebetween and said track projection member being fitted to said case body with said track projection fitted against said stepped portion, and said track groove of said loop taker comprises a U-shaped coating layer of synthetic resin material having a small coefficient of friction on said bottom wall and said pair of sidewalls of said track groove. 
     
     
       5. The rotating hook of claim 4, wherein said loop taker comprises a steel body. 
     
     
       6. The rotating hook of claim 4, wherein said loop taker includes adhesive means for bonding said coating layer to said track groove. 
     
     
       7. The rotating hook of claim 4, wherein said coating layer is a porous spongy synthetic resin material having small holes therein for retaining lubricant oil. 
     
     
       8. A fully rotating hook comprising a metal inner bobbin case extending in an axial direction, a metal outer loop taker mounted about said bobbin case, said loop taker having a track groove formed by a bottom wall and a pair of sidewalls therein, means for rotating said loop taker such that relative rotation occurs between said loop taker and said bobbin case, and stopper means for preventing rotation of said bobbin case with said loop taker while said loop taker is rotating, the improvement wherein said inner bobbin case comprises a case body having a fitting portion extending in said axial direction and accommodated in said loop taker and a track projection member made of synthetic resin material having a substantially low coefficient of friction and removably fixed to said fitting portion of said case body, said track projection member comprising a flange-like track projection fitting with said track groove of said loop taker and a surrounding portion extending in said axial direction for fixing said track projection member to said fitting portion of said case body, said track projection member being removably fixed to said case body with a plurality of screws extending radially between said surrounding portion of said track projection member and said fitting portion of said case body, and said track groove of said loop taker comprising a U-shaped coating layer of porous synthetic resin material having a small coefficient of friction and small holes therein for retaining lubricant oil on said bottom wall and said pair of sidewalls of said track groove.